The present invention relates to a bulk semiconductor logic device and more particularly to a semiconductor device including a cathode and an anode for applying a bias electric field to a semiconductor exhibiting negative conductivity under high electric field, a region where the electric field is locally lower than that in the other regions, and at least two signal electrodes of field effect type additionally provided in the region of the lower field to which signals are supplied to control the generation of high electric field domains in the semiconductor for the performance of logical operations.
It is well-known in the art that in a semiconductor exhibiting negative conductivity under a high electric field, application of an electric field exceeding the threshold value of the semiconductor causes generation of a high electric field domain (a phenomenon known as the Gunn effect). It is further known that when a control electrode is provided on said device and a signal is applied to said electrode, generation of high electric field domains can be permitted or prevented, making possible a high speed logical operation. The structure of conventional devices for controlling the generation of high electric field domains in the semiconductor is such that a cathode and an anode are provided for biasing at each end of a semiconductor of uniform cross-section and resistivity to maintain the electric field in said semiconductor uniform and below the threshold value, and a high electric field domain is generated either by raising the electric field of the entire semiconductor by supplying a signal to the cathode or the anode or, by applying a signal voltage to an additional high electric field domain generating electrode provided on the semiconductor by means of Schottky junction, etc., to raise the electric field only in the region under the additional electrode.
The above structure, however, has disadvantages. First, the degree of fan-out obtainable is small if a high electric field domain is generated through application of a signal voltage to the cathode or the anode because of the low impedance between the cathode and anode. Second, when an additional high electric field domain generating electrode is used in a semiconductor of uniform section, a high electric field domain is apt to be generated under the electrode even in the absence of signal voltage application. And third, the bias electric field must be maintained considerably lower than the threshold value in order to overcome the second disadvantage and ensure stable control of high electric field domain generation. However, since decreasing the bias electric field gives decreased output voltage in the said Gunn effect, there is an output signal drop.